March 2017
Intermediate to advanced
364 pages
9h 45m
Japanese
Content preview from 初めてのPHP
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77
5
章
ロジックのグループ：関数とファイル
プログラムを書くときに、不精であることは長所になります。今までに書いたコードを再利用す
ると、作業を極力少なくするのが容易になります。関数（function）がコードを再利用するための
鍵となります。関数とは、命令文を入力し直す代わりに関数名を呼び出して実行できる名前付きの
命令文の集合です。これにより、時間を節約でき、間違いを避けることができます。加えて、関数
を使うと、他の人々が書いたコードを簡単に利用できるようになります（PHP エンジンの開発者が
書いた組み込み関数を利用するとわかります）。
独自の関数を定義して使用する際の基本は、「5.1.1関数の宣言と呼び出し」で説明します。関数
を呼び出すときには、操作する値を渡せます。例えば、ユーザが現在の Web ページにアクセスで
きるかどうかチェックするための関数を書く場合、ユーザ名と現在の Web ページ名を関数
に与え
る必要があります。このような値を引数と呼びます。「5.2 関数へ引数を渡す」では、引数を受け
取る関数の書き方と関数内での引数の使い方について説明します。
関数には一方通行のものもあります。引数は渡せますが、何も返しません。HTML ページの先
頭部分を出力する
print_header
関数はページのタイトルを含む引数を取りますが、実行後には何
の情報も返しません。出力を表示するだけです。ほとんどの関数は双方向に情報をやり取りします。
前述したアクセス制御関数はその一例です。アクセス制御関数は ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.